I will try over the next few days post more details on the design. I did not develop a schematic of the entire amp, but since it was modular, and based on well documented schematics, just selected values appropriate for the operating points selected.
1. PASS BA Complimentary Output stage - I just built this based on the recommended parts list in the DIYAudio.com Build Guide. I did buy tightly matched MOSFETS (IRFP240 and IRFP9240) from a reliable Ebay vendor (moniker: hotshotaudio). You can also get the same from the DIYAudio.com store for around the same price (the DIYAudio store was out of matched sets when I was putting together the amp). Also buy Keratherm pads, MUCH easier than using mica and thermal paste. I used KOA Speer metal oxide source resistors (2W/0.47 ohm/5% tolerance) and matched them, but if you want to be fancy, you can use metal foil, thick film, or whatever. The E-caps in the bias supply are Elna Silmic II.
2. Aikido stage. I have to review what I used, but I believe I used 470 ohm/0.5W PRP resistors for the cathode resistors in the voltage amplifier stage and a 150 ohm/0.5W PRP for the cathode resistor in the tail of the bottom tube of the White follower (I have to check on both of these values). Carbon comp gridstoppers throughout, as well as PRP or quality metal films for voltage dividers, ground references, etc.. Used audio quality film HV power supply bypass capactors (10 uF or so) at the board. Also used a 1100 ohm/10W wirewound resistor in series from this capacitor to the plate of the top tube in the White follower. I am using a 6N1P or 6CG7 input tube, with a 6N6 white follower, as previously discussed.
3. MOSFET Power supply - I used an ANTEK AS-4220 400VA/20V toroidal transformer for a stereo amp (300VA/18V is the base recommendation). I get a slightly higher rail voltage (24VDC rather than 22VDC), but possible to go up further. The DIYAudio Universal Power Supply board is built according to the DIYAudio.com Build Guide, and recommended parts list, only I left off the resistors between the two capacitor banks and used a choke instead (because I had them). The chokes are Hammond 159ZJ 10mH/5A. I did put in some large film bypass caps in parallel with the second bank of E-caps, these ideally should be located at the Output board. Recommend using the best, 105C, long life E-caps in the supply you can find. I believe I have some top grade Nichicons.
4. Aikido Power supply (one per channel) - This is a pretty basic preamp type supply, using a Hammond 250VCT/100mA + 6.3VAC/2A (I think a 269AX). Used a Broskie PS-7 power supply kit in a bridge configuration, replacing the supplied E-caps with high quality, larger value Nichicon at the output (kept the input cap the same value). Instead of the supplied resistor for CRC, I used a 10H/50mA (Triad) choke for a CLC supply. B+ is around 320V based on memory (need to check). Heater supply is AC, with a voltage divider of the B+ for 75VDC offset for noise.
5. Chassis - Used the 4U Deluxe chassis from ModuShop sold through DIYAUDIO.com.
6. You will need alot of 3mm standoffs, capscrews, etc. Really easy these days through Amazon.
Well, this fills in some of the details on the amp. Let me know if you need more info or would like me to check something on my build.
David
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